I get really anxious at the beginning of relationships and I tend to overthink everything, how can I stop doing this?

Whenever I start talking to someone, I overthink/over analyze everything. If I don't hear back for a couple hours I immediately jump to the conclusion that I must have messed something up. This has happened with every relationship I have been in, I am just constantly stressed until things either progress past the initial courtship phase or until they end.

I do a good job of not showing this to the person I am talking to, or at least I think I do. I don't bombard them with texts if I didn't hear back. But it really affects me, and it can make me depressed/anxious.

In general I have a tendency to over analyze everything, I'm pretty observant and can normally tell if something is wrong or off. But it seems like most times, just because something is off doesn't mean it's bad. For example, been talking to a girl recently, didn't hear back from her for almost a full day, I spent most of that day incredibly stressed out, checking to see if she had seen my message and just waiting for a reply. But then she texted me apologizing for taking so long to respond and that she was with family. I think I get so stressed out because I constantly have my phone next to me, so I normally am able to respond pretty quickly. But not everyone is like that, some people can be away from their phones, but it's hard for me to get around the fact that other people aren't like me with technology.